Method of producing printing plates



Patented Dec. 9, 1924.

IPHILIIPP MllLLER, OF STEC-LITZ, NEAR BERLIN, GER-MANY.

No Drawing.

(GRANTEDUNDER THE PROVISIONS T 0 all whom it may Be it known that citizen of Germany,

TES

METHOD O13 PRODUCING PRINTING PLATES.

Application filed August 30, 1921.

co-ncem: I, PHILIP}? MiiLLnn. a reslding at Steghtz,

near Berlin, Holsteinischestreet 29, Ger- 5 many, have invented certain new and use ful Improvements in a Method of Producing Printing Plates (said invention having been patented in Germany No. 30?),ll0, ap-

plication filed February 27, 1917), of which the following is a specification.

My invention relates to a new and im proved method for producing photomechanical printing plates.

As is well known, photomechanical printing plates have many years been manufactured for by causing a layer of eelatine or the like, which has been rendered sensitive to light by admixture with potassium bichromate or the like. to be spread upon a suitable plate made of metal or other materials.

W hen gelatlne or some corresponding colloid which has been rendered sensitive to light by admixture is acted upon by insoluble. Hence with various substances. light, it becomes relatively after an exposed plate has been developed. and washed, the image is reproduced in a nelatine reprodu acid preferably relatively layer on the metal plate.

insoluble gelatine By protectingthis ction from the action of by impregnating it with a suitable oily transfer ink, the metal plate can be etched so that a completed printing" plate is produced.

ACCOTdlTlQ' to my improvements. the developed and washed plate is treated so as to visually reproduce all the lines, including the soft lines in the drawing or picture which it is desired to reproduce by the printing process.

h as preferably all acid. therefrom.

This is accomplished by treatwashed plate which by means of a fatty coloring material contained in what may he called a grinding adapted to cause solution and which is the plate to receive the color at those places at which the sheet has been acted upon by the light. and according to the degree to which it has been subjected to the action of the light.

This enables the operator to check up the character of the photographic work, and the gelatine reproduction of the images becomes strongly impregn ated with the ink or color- OF THE ACT (3F MARCH 3, 1921, 4-1 STAT.

ing material, so that it is protected from the action. of the etching acid, and also serves to reprint the original image.

According to my invention, 1 preferably do not use glycerine as a carrying agent for the color because the use of glycerine wil not enable all the soft lines in the picture, drawing or the like to be reproduced. This is because glycerine attacks the gelatine reproduction of the image.

I prefer to use substances having hygroscopic qualities such as concentrated solutions of the chlorides of the alkaline earth metals such as .the chlorides of calcium, of magnesium. or the like.

When these concentrated solutions are used as carrying agents for the color, the plate takes up the color at the places at which it has been acted upon by the light as well as if glycerine were used, but the color is later removed in a great many places because of the etching and washing operations.

I therefore prefer to add to the concentrated solutions of the chlorides before mentioned. a solution of resins in alcohol together with a suitable quantity of a fatty or oily transfer ink or color. I have found a solution of three parts of colophony. or shellac. in forty parts by weight of alcohol to be suitable.

About two drops of hydrochloric acid may also be added to the concentrated solution of the chlorides before mentioned. This minute amount of hydrochloric acid is not necessary but does not impair the effect of the solution. The minute amount of hydrochloric acid causes the ink to adhere to the metal plate alone: the lines of the exposed and hardened Q'Slfltlfifi The mixture thus formed is spread upon the developed plate in the usual manner by means of a sponge or the like. until. the drawing: or picture has a deep black color.

The use of the calcium or magnesium chloride prevents the color from separating at the .e'elatine sheet. In addition. the drawing. picture or the like is made visible in a durable manner so that any damaged places may be further developed. The colophony or the like, together with the reprinting colors are fixed upon the lines of the drawing, picture or the like, so that good and permanent color lines are produced.

The alcohol only serves to dissolve the resin and it is allowed to evaporate as the ink is applied.

This new process is especially advantageous When plates of zinc or aluminum are used. It is obvious that by my new and improved process, I have replaced the glycerin'e by a cheaper material which serves to firmly fix the color upon the developed lines of the gelatine plate. After the hardened gelatine has been thus impregnated with the ink and protected by the resin, the plate can be washed to remove the ink from the points corresponding to the dark spots of the image, and the plate can then be etched and used for printing.

I havedescribed a preferred embodiment of my invention but it is clear that numerous changes and omissions could be made without departing from its spirit.

1. In the art of producing photomechanical printing plates made of metal with a colloid layer sensitive to light, those steps which consist in treating the exposed plate with an oily ink held in a solution of a chlo ride of an alkaline earth metal, said solution also containing a solution of a resin ina volatile solvent which is allowed to evaporate.

2. In the art of producing photomechauical printing plates made of metal with a colloid layer sensitive to light, that step which consists in impregnating the lines of colloid on to the bright part of the image with coloring matter and protecting said lines With a substance resistant to acid, before etching said plate. I

3.1a method according to claim 1, in which the resin iscolophony.

In testimony whereof l hereunto affix my signature. 7

PHILIPP MULLER.

the exposed plate corresponding 

